SituationalVariables related to the situation such as the amount of light, wind, water and soil composition in an experiment on plants.
ParticipantVariables related to participants such as the age and gender of people in a medical study.
Demand CharacteristicsWhat participants know about the research. For example, in a psychology study participants may change responses to fit what they think is expected.
ExperimenterVariables related to the people conducting the experiment. For example, an experiment where seven researchers take proper measurements and an eight researcher takes incorrect measurements because they have a fundamental misunderstanding about the equipment or process used in the measurement.
Confounding VariableA confounding variable is a variable that influences both the independent and dependent variables in an experiment. This is often a flaw in experimental procedures or equipment. For example, an experiment on a plant fertilizer where too much water is applied to the plants causing the fertilizer to run off and the plants to die.
|Overview: Extraneous Variables|
Variables that can influence an experiment that aren't the independent variables that you are testing.